scholarly journals Glycerol Hydrogenolysis to 1,2-Propanediol over Novel Cu/ZrO2 Catalysts

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 72
Author(s):  
Giuseppina Luciani ◽  
Giovanna Ruoppolo ◽  
Gianluca Landi ◽  
Valentina Gargiulo ◽  
Michela Alfè ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Copper Deposition ◽  
Biodiesel Production ◽  
Preparation Methods ◽  
Glycerol Hydrogenolysis

Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.

Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide by Heteropolyacid/Metal Oxide Catalysts

2007 ◽  
Vol 119 ◽  
pp. 287-290 ◽  
Author(s):  
Kyung Won La ◽  
Min Hye Youn ◽  
Jin Suk Chung ◽  
Sung Hyeon Baeck ◽  
In Kyu Song
Keyword(s):  
Carbon Dioxide ◽  
Metal Oxide ◽  
Dimethyl Carbonate ◽  
Batch Reactor ◽  
Direct Synthesis ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Pure Ceo2 ◽  
Autoclave Reactor

CexTi1-xO2 and H3PW12O40/CexTi1-xO2 catalysts were prepared by sol-gel method, and they were applied to the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in a batch reactor. The reaction was carried out in an autoclave reactor at 170oC and 5 MPa. It was found that CexTi1-xO2 exhibited a higher catalytic performance than pure CeO2 and TiO2. The catalytic performance of CexTi1-xO2 was the maximum when x=0.1. It was also revealed that H3PW12O40/CexTi1-xO2 catalysts showed a remarkably enhanced catalytic performance than the corresponding CexTi1-xO2 catalysts. The amount of DMC produced by 15 wt% H3PW12O40/ Ce0.1Ti0.9O2 catalyst was six times higher than that produced by Ce0.1Ti0.9O2 catalyst. It is concluded that both Brönsted acid sites provided by H3PW12O40 and base sites in CexTi1-xO2 played an important role in improving the catalytic performance of H3PW12O40/CexTi1-xO2.

scholarly journals Ethanol Dehydration over WO3/TiO2Catalysts Using Titania Derived from Sol-Gel and Solvothermal Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Anchale Tresatayawed ◽  
Peangpit Glinrun ◽  
Bunjerd Jongsomjit
Keyword(s):  
Physicochemical Properties ◽  
Pore Volume ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Acid Sites ◽  
Ethanol Conversion ◽  
Ethanol Dehydration ◽  
Preparation Methods ◽  
Solvothermal Methods ◽  
Different Characteristics

The present study aims to investigate the catalytic ethanol dehydration to higher value products including ethylene, diethyl ether (DEE), and acetaldehyde. The catalysts used for this reaction were WO3/TiO2catalysts having W loading of 13.5 wt.%. For a comparative study, the TiO2supports employed were varied by two different preparation methods including the sol-gel and solvothermal-derived TiO2supports, denoted as TiO2-SG and TiO2-SV, respectively. It is obvious that the different preparation methods essentially altered the physicochemical properties of TiO2supports. It was found that the TiO2-SV exhibited higher surface area and pore volume and larger amounts of acid sites than those of TiO2-SG. As a consequence, different characteristics of support apparently affected the catalytic properties of WO3/TiO2catalysts. As expected, both catalysts WO3/TiO2-SG and WO3/TiO2-SV exhibited increased ethanol conversion with increasing temperatures from 200 to 400°C. It appeared that the highest ethanol conversion (ca. 88%) at 400°C was achieved by the WO3/TiO2-SV catalysts due to its high acidity. It is worth noting that the presence of WO3onto TiO2-SV yielded a remarkable increase in DEE selectivity (ca. 68%) at 250°C. In summary, WO3/TiO2-SV catalyst is promising to convert ethanol into ethylene and DEE, having the highest ethylene yield of ca. 77% at 400°C and highest DEE yield of ca. 26% at 250°C. These can be attributed to proper pore structure, acidity, and distribution of WO3.

Pt/UiO-66 Nanocomposites as Catalysts for CO2 Methanation Process

2019 ◽  
Vol 19 (6) ◽  
pp. 3187-3196 ◽  
Author(s):  
Maria Mihet ◽  
Gabriela Blanita ◽  
Monica Dan ◽  
Lucian Barbu-Tudoran ◽  
Mihaela D Lazar
Keyword(s):  
Thermal Stability ◽  
Surface Area ◽  
Metal Organic Framework ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
High Dispersion ◽  
Co2 Methanation ◽  
Preparation Methods ◽  
Good Thermal Stability ◽  
Catalytic Support

Pt/UiO-66 nanocomposites with platinum target concentration of 3 wt.% were prepared by 3 preparation methods, characterized and tested in the CO2 methanation process. Choice of the microporous UiO-66 metal-organic framework (Zr6O4(OH)4 with 1,4-benzene-dicarboxylate ligand) as catalytic support was motivated by the CO2 chemisorption capacity (proven by CO2-TPD profiles), large specific surface area (1477 m2/g) which favors a high dispersion of metal nanoparticles and good thermal stability. The preparation methods for the Pt/UiO-66 nanocomposites are: (1) wetimpregnation followed by reduction in H2 at 200 °C for 2 h; (2) wet-impregnation followed by reduction with an aqueous solution of NaBH4; and (3) “double-solvent” method, followed by reduction with NaBH4. The UiO-66 based nanocomposites were characterized by N2 adsorption–desorption (BET method), XRD, and SEM/TEM. The Pt/UiO-66 catalyst prepared by method 3 was chosen for catalytic testing due to its highest surface area, smallest platinum nanoparticles (PtNPs) size, the localization of PtNPs both on the grain’s internal and external surface and best thermal stability in the desired temperature range. Its capacity to adsorb and activate CO2 and H2 was evaluated in thermo-programmed desorption experiments (H2-TPD and CO2-TPD). Hydrogen is molecularly adsorbed, while CO2 is adsorbed both molecularly and dissociatively. The catalytic performance in the CO2 methanation process was evaluated by Temperature Programmed Reactions (TPRea, 2 °C/min, 30–350 °C), at atmospheric pressure. The best results were obtained at 350 °C, CO2:H2 molar ratio of 1:5.2 and GHSV ═ 1650 h−1. In these conditions CO2 conversion is almost 50% and CH4 selectivity is 36%, the rest of the converted CO2 being transformed in CO.

scholarly journals The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 314
Author(s):  
Xing Ning ◽  
Zhi-bo Xiong ◽  
Bin Yang ◽  
Wei Lu ◽  
Shui-mu Wu
Keyword(s):  
Nitric Acid ◽  
Citric Acid ◽  
Sol Gel ◽  
Nox Reduction ◽  
Combustion Process ◽  
Catalytic Performance ◽  
Metal Nitrate ◽  
Acid Sites ◽  
Complexing Agent ◽  
Nh3 Scr

Sol-gel spread self-combustion is the burning of the complexing agent in dried gel and the oxidant. Meanwhile, high temperature takes place during the combustion process, which is harmful to the pore structure of the catalyst. The nitrate from metal nitrate precursors as an oxidant could participate in the spread of the self-combustion process. Therefore, the influence of nitrate from metal nitrate on the spread self-combustion of an iron–cerium–tungsten citric acid gel and its catalytic performance of NOx reduction were investigated by removing nitrate via the dissolution of washing co-precipitation with citric acid and re-introducing nitric acid into the former solution. It was found that the removal of nitrate contributes to enhancing the NH3–SCR activity of the magnetic mixed oxide catalyst. The NOx reduction efficiency was close to 100% for Fe85Ce10W5–CP–CA at 250 °C while the highest was only 80% for the others. The results of thermal analysis demonstrate that the spread self-combustion process of citric acid dried gel is enhanced by re-introducing nitric acid into the citric acid dissolved solution when compared with the removal of nitrate. In addition, the removal of nitrate helps in the formation of γ-Fe2O3 crystallite in the catalyst, refining the particle size of the catalyst and increasing its pore volume. The removal of nitrate also contributes to the formation of Lewis acid sites and Brønsted acid sites on the surface of the catalyst compared with the re-introduction of nitric acid. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrates that both Eley–Rideal (E–R) and Langmuir–Hinshelwood (L–H) mechanisms exist over Fe85Ce10W5–CP–CA at 250 °C with E–R as its main mechanism.

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by Perchlorated Zirconia (HClO4/ZrO2) nanoparticles as a novel solid acid catalyst

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Seyed Yousef Mosavian
Keyword(s):  
Solid Acid ◽  
Condensation Reaction ◽  
Solid Acid Catalyst ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Zro2 Nanoparticles ◽  
Calcination Temperatures ◽  
Aldehydes And Ketones

Zirconia was synthesized in nanosize by sol-gel method and perchlorated zirconia (HClO4/ZrO2) with various calcination temperatures were prepared and characterized by XRD, FTIR and SEM techniques. The catalyst acidity characters, including the acidicstrength and the total number of acid sites were determined by potentiometric titration. The catalytic performance experiments show that the HClO4/ZrO2 with calcination temperature of 300 °C has the best catalytic activity. 2,3-Dihydroquinazolin-4(1H)-ones wereprepared in good to excellent yields via condensation reaction of oaminobenzamide and various types of aldehydes and ketones in the presence of HClO4/ZrO2 nanoparticles as an efficient solid acid catalyst. The catalyst is reusable with moderate loss in activity.

Effect of Rice Husk Ash Based Silicon Dioxide on the Properties of SUZ-4 Zeolite

2017 ◽  
Vol 729 ◽  
pp. 24-29
Author(s):  
Thitipob Sirisoontornpanit ◽  
Atichat Wongkoblab ◽  
Supunnee Junpirom
Keyword(s):  
Silicon Dioxide ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Weak Acid ◽  
Molar Ratio ◽  
Temperature Programmed

SUZ-4 zeolite was synthesized by the sol-gel technique, followed by hydrothermal process. The effect of the molar ratio of rice husk ash based silicon dioxide to silica solution was investigated. The synthesized zeolite was characterized by XRD, SEM, N2 adsorption and temperature programmed desorption. The results show that the SUZ-4 zeolite was formed for all investigated conditions. However, the formation of MER zeolite occurred as an impurity for the content of rice husk ash higher than 75%. A needle shape crystal with mainly microporous structure is the feature of synthesized SUZ-4 zeolite. The result of temperature programmed desorption indicated that the chemical surface property of obtained SUZ-4 zeolite was weak acid sites.

Efficient conversion of cotton stalks over a Fe modified HZSM-5 catalyst under microwave irradiation

RSC Advances ◽  
2016 ◽  
Vol 6 (34) ◽  
pp. 28532-28537 ◽  
Author(s):  
Xiangjin Kong ◽  
Xiaole Li ◽  
Shuxiang Wu ◽  
Xin Zhang ◽  
Junhai Liu
Keyword(s):  
Microwave Irradiation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Cotton Stalk ◽  
Efficient Conversion ◽  
Fe Species ◽  
Cotton Stalks ◽  
Bio Oil

Doped amounts of Fe species to HZSM-5 distinctly improved the catalytic performance of the catalyst for the liquefaction of cotton stalk to bio-oil due to the enhanced total and weak acid sites.

scholarly journals The influence of composition on the functionality of hybrid CuO–ZnO–Al2O3/HZSM-5 for the synthesis of DME from CO2 hydrogenation

RSC Advances ◽  
2018 ◽  
Vol 8 (53) ◽  
pp. 30387-30395 ◽  
Author(s):  
Yubing Hu ◽  
Yajing Zhang ◽  
Jie Du ◽  
Chunyan Li ◽  
Kangjun Wang ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Co2 Hydrogenation ◽  
Chemical State

The introduction of Al2O3 increased the number of weak acid sites, altered the copper chemical state and improved the catalytic performance and stability consequently.

Synthesis and Catalytic Application of Mesoporous Molecular Sieves MCM-41 Containing Niobium and Tantalum

2007 ◽  
Vol 124-126 ◽  
pp. 1761-1764 ◽  
Author(s):  
Hun Jung ◽  
Kwang Deog Jung ◽  
Oh Shim Joo ◽  
Sun Jin Kim
Keyword(s):  
Vapor Phase ◽  
Molecular Sieves ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Beckmann Rearrangement ◽  
Mesoporous Molecular Sieves ◽  
Cyclohexanone Oxime ◽  
Catalytic Application ◽  
Mcm 41

Niobium- and tantalum-containing mesoporous molecular sieves MCM-41 have been synthesized, and applied as a catalyst for vapor phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. NbMCM-41 catalyst exhibited high catalytic performance in the vapor phase Beckmann rearrangement of cyclohexanone oxime. The oxime conversions were almost 100% and the lactam selectivities were around 80%. The lactam selectivities of NbMCM-41 catalyst were higher than those of AlMCM-41 catalyst. However, TaMCM-41 catalyst exhibited lower catalytic performance than AlMCM-41 catalyst, and it was fast deactivated with time. These results may be due to the acidity difference among the catalysts. The results from NH3-TPD showed that NbMCM-41 catalyst possessed weak and medium acid sites, while TaMCM-41 catalyst possessed only very weak acid sites. AlMCM-41 catalyst also exhibited only weak acid sites.

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